The invention relates to a metering receptacle with an elongate hollow body which at one end comprises a closable exit opening and which at the other end is closable by way of a plastic plunger stopper which is accommodated in the hollow body in a longitudinally displaceable manner by way of a plunger rod.
Metering receptacles of this type are used in numerous application fields with a different specific design; for example for medical purposes (pharmaceutics and diagnostics) or for cosmetic applications as syringes with a syringe cylinder as a hollow body, or as plunger burettes in chemical analysis or as a dispenser.
Of particular importance with this are the prefilled disposable syringes, also called ready syringes or the prefilled disposable plunger burettes. Ready syringes of glass are for example known from DIN ISO 11040-4. Ready syringes of plastic are e.g. described in DE 44 38 360 A1. Prefilled disposable burettes are the subject-matter of DE 196 52 780.
With these prefilled ready syringes or plunger burettes it is necessary to incorporate a sliding layer onto the inside of the hollow body of the metering receptacle, in particular of the syringe body in order for the application to achieve sufficiently low friction forces on displacing the elastomer plunger. Only thus is a sufficiently fine-touch metering of the contents of the metering receptacle possible.
The incorporation of such sliding layers may be effected in various ways, as this is for example described in detail in DE 197 53 766.9 A1, which corresponds to U.S. Pat. No. 6,296,893. With glass syringes this is typically achieved by depositing and burning-in silicone emulsions at over 300°C., as is described in the article R. D. Anand, “Die Pharmazeutische Industrie” (The Pharmaceutical Industry) 54 No. 1, 1992, pages 69-73, “Spritzampullen: Em Vergleich in Zusammensetzung, Verarbeitung and Gebrauch vorgefuellter Spritzen” (Syringe ampullas: a comparison in composition, processing and use of prefilled syringes).
Sliding layers may likewise be deposited according to EP 0 202 915 B1 likewise with ionizing plasmas, wherein likewise silicon oil in the form of polydialkyl siloxane is used.
Furthermore, according to EP 0 338 671 B 1, which corresponds to U.S. Pat. No. 5,009,646, well sliding elastomer plungers may be manufactured when the elastomer plunger is coated with a special film material and has suitable dimensions. Although the use of special coating materials for elastomer plungers is a way of largely avoiding silicone as a lubricant, the manufacture of corresponding plunger stoppers is very expensive and significantly limits the geometric choice.
The use of sliding films based on silicon oil however has grave disadvantages, in particular with the use of the metering receptacle for medical purposes, in particular as a prefilled disposable syringe. Thus there may easily occur an interaction of the content substances, of the medicament with the silicon oil layer and with this essential active ingredients may be adsorbed by the silicon layer. Furthermore, a detaching of silicon oil droplets and/or flakes during the storage of the medicament may easily occur. Such problems are e.g. dicussed by V. Langlade and L. Caburet in “CURRENT ISSUES IN PACKAGING OF COMMON DILUENTS IN PREFILLED SYRINGES” PDA Fourth International Congress, Exhibition & Workshops Proceedings, page 153-page 165, 19-23 Feb. 1996.
Similiarly with prefilled plunger burettes there may occur disadvantageous interactions between the contents of the burette and the silicone layer.
By way of DE 38 83 985 T 2 there is known a syringe for medical purposes which has good sliding properties of the plunger in the syringe body and requires no silicone sliding layer.
With the known syringe the elastomer plunger at the location at which it slides on the inner wall of the syringe cylinder has a fluroplastic plastic layer with a low dynamic friction coefficient and a thickness of approx. 5 m which is deposited by the method of low-temperature plasma polymerization.
Disregarding the expensive manufacture of such a plunger stopper, the known silicone-free syringe has the disadvantage that the coating material is very expensive and to a very limited degree is compatible to medication and capable of sterilization. Furthermore the micro-sealedness is not sufficiently given since the material comprises pores and is also not flexible enough, i.e. may not conform sufficiently sealingly on the inner wall of the syringe body.